Elemental Abundancies in the X-ray Gas of Early-type Galaxies with XMM-Newton and Chandra Observations

Abstract

The source of hot gas in elliptical galaxies is thought to be due to stellar mass loss, with contributions from supernova (SN) events and possibly from infall from a surrounding environment. This picture predicts supersolar values for the metallicity of the gas toward the inner part of the galaxy, which can be tested by measuring the gas phase abundances. We use high-quality data for 10 nearby early-type galaxy from XMM-Newton, featuring both the European Photon Imaging Camera and the Reflection Grating Spectrometer, where the strongest emission lines are detected with little blending; some Chandra data are also used. We find excellent consistency in the elemental abundances between the different XMM-Newton instruments and good consistency with Chandra. Differences in abundances with aperture size and model complexity are examined, but large differences rarely occur. For a twotemperature thermal model plus a point source contribution, the median Fe and O abundances are 0.86 and 0.44 of the solar value, while Si and Mg abundances are similar to that for Fe. This is similar to stellar abundances for these galaxies but SNe were expected to enhance the gas phase abundances considerably, which is not observed.

Description
Keywords
cooling flows, galaxies: abundances, galaxies: elliptical and lenticular, cD, galaxies: individual (NGC 720, NGC 1399, NGC 3923, NGC 4406, NGC 4472, NGC 4553, NGC 4636, NGC 4649, NGC 5044, IC 1459), X-rays: galaxies
Citation
Ji, J., et al. (2009): Elemental Abundancies in the X-ray Gas of Early-type Galaxies with XMM-Newton and Chandra Observations. The Astrophysical Journal, 696(2).